From owner-svn-src-user@FreeBSD.ORG Mon Nov 22 08:19:19 2010
Return-Path: <owner-svn-src-user@FreeBSD.ORG>
Delivered-To: svn-src-user@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
by hub.freebsd.org (Postfix) with ESMTP id 631B7106564A;
Mon, 22 Nov 2010 08:19:19 +0000 (UTC)
(envelope-from davidxu@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
by mx1.freebsd.org (Postfix) with ESMTP id 51D928FC08;
Mon, 22 Nov 2010 08:19:19 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id oAM8JJ2W083049;
Mon, 22 Nov 2010 08:19:19 GMT (envelope-from davidxu@svn.freebsd.org)
Received: (from davidxu@localhost)
by svn.freebsd.org (8.14.3/8.14.3/Submit) id oAM8JJFA083047;
Mon, 22 Nov 2010 08:19:19 GMT (envelope-from davidxu@svn.freebsd.org)
Message-Id: <201011220819.oAM8JJFA083047@svn.freebsd.org>
From: David Xu <davidxu@FreeBSD.org>
Date: Mon, 22 Nov 2010 08:19:19 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-user@freebsd.org
X-SVN-Group: user
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc:
Subject: svn commit: r215660 - user/davidxu/libthr/sys/kern
X-BeenThere: svn-src-user@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the experimental " user"
src tree" <svn-src-user.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-user>,
<mailto:svn-src-user-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-user>
List-Post: <mailto:svn-src-user@freebsd.org>
List-Help: <mailto:svn-src-user-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-user>,
<mailto:svn-src-user-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 22 Nov 2010 08:19:19 -0000
Author: davidxu
Date: Mon Nov 22 08:19:18 2010
New Revision: 215660
URL: http://svn.freebsd.org/changeset/base/215660
Log:
Merge from r215652:
Use atomic instruction to set _has_writer, otherwise there is a race
causes userland to not wake up a thread sleeping in kernel.
Modified:
user/davidxu/libthr/sys/kern/kern_umtx.c
Modified: user/davidxu/libthr/sys/kern/kern_umtx.c
==============================================================================
--- user/davidxu/libthr/sys/kern/kern_umtx.c Mon Nov 22 07:17:27 2010 (r215659)
+++ user/davidxu/libthr/sys/kern/kern_umtx.c Mon Nov 22 08:19:18 2010 (r215660)
@@ -3565,9 +3565,8 @@ do_sem_wait(struct thread *td, struct _u
umtxq_insert(uq);
umtxq_unlock(&uq->uq_key);
- /* Don't modify cacheline when unnecessary. */
if (fuword32(__DEVOLATILE(uint32_t *, &sem->_has_waiters)) == 0)
- suword32(__DEVOLATILE(uint32_t *, &sem->_has_waiters), 1);
+ casuword32(__DEVOLATILE(uint32_t *, &sem->_has_waiters), 0, 1);
count = fuword32(__DEVOLATILE(uint32_t *, &sem->_count));
if (count != 0) {